Israel has said one of the top goals of its Gaza operation is the destruction of Hamas' underground tunnels. Randi Kaye looks at how Hamas claims to use them, and why Israel is so intent on destroying them.

For the first time in history there will be ebola patients on U.S. soil. Two American aid workers infected with the deadly virus will be brought home from Liberia on a medical charter flight. They are among more than 1,300 people who have contracted the disease in West Africa. So far, at least 729 people have died. Dr. Sanjay Gupta talks about the plans for treating the two gravely ill Americans when they arrive.

For the first time in days, investigators were able to reach the crash site of Malaysia Airlines Flight 17. OSCE spokesman Michael Bociurkiw describes crossing the front lines of the raging conflict in Eastern Ukraine. He also shares photos and explains why the investigation now needs to kick into high gear.

Expectations and emotions are high after the news of a 72-hour ceasefire deal in Gaza. Maen Areikat is the Chief of the PLO delegation in Washington. He tells Anderson that Palestinians will only agree to demilitarization when Israel ends its occupation of Gaza.

Daniel Ayalon is a former Israeli Ambassador to the United States. He denies that his country is occupying Gaza and explains to Anderson that Israel now needs to see Hamas stop its attacks.

Artillery hit a United Nations school in Gaza that was sheltering thousands of Palestinians. An initial review by the Israeli military found that its forces were responding to nearby mortar fire. The United Nations and the White House condemned the attack. Karl Penhaul got an up close look at the immediate aftermath.

Anderson discussed the deadly attack with Pierre Krahenbuhl, who is the Director of Operations for the U.N. Relief and Works Agency.

Two Americans who were fighting on the front lines of the Ebola outbreak are now fighting for their lives. Missionary Nancy Writebol is one of those infected. Her friend and pastor John Munro says that she is holding her own in her life-and-death battle.

Investigators in Ukraine tried and failed again today to reach the scene of the Flight 17 crash. Though they haven't set foot on the site, analysts are gleaning information by looking at the location of the wreckage and photos of the debris. The Wall Street Journal catalogued and mapped the crash site. Anderson and CNN safety analyst David Soucie looked at what the debris field tells us.

The Republican-led house voted 225 to 201 to sue President Obama over the Affordable Care Act. Not a single Democrat voted for the resolution. The suit claims the president abused his power, and it is sparking plenty of talk about impeachment. Chief Congressional Correspondent Dana Bash described the situation as uncharted territory.

Authorities in Gaza say more than 1,300 people have been killed there since the war began. The United Nations estimates 70-80% of the dead were civilians. 56 Israelis have been killed, all but three were troops. That disparity drives a perception in parts of the world, that the war is, if not wrong outright, then at least it is being wrongly fought. In Israel, there is overwhelming public support, with approval between 80-90%. Ron Dermer is Israel's Ambassador to the United States.

The kidnapping and murder of three Israeli teens just weeks ago, helped escalate already simmering tensions between Israel and Palestinian militants. While speaking to Anderson Cooper last night, Israeli government spokesman Mark Regev blamed Hamas for their deaths. On the same program, Mouin Rabbani, a senior fellow at the Institute for Palestine Studies cast doubt on that claim and pointed out that Israel has provided no evidence that these killings were the work of Hamas. Randi Kaye takes a closer look at the murders and the fallout.